An audio recording features a researcher delivering a university seminar on the non-invasive spectral analysis of pre-Columbian pictorial manuscripts:
"Good morning, colleagues. Today I am presenting our laboratory's recent investigation into the sixteenth-century Mixtec manuscript known as the Codex Selden. For centuries, scholars suspected that this deer-hide manuscript was a palimpsest—meaning an earlier pictorial narrative lay concealed beneath its opaque layer of gesso, a chalk-and-animal-glue primer. Traditional radiography had failed because organic pigments lack the radio-opacity of metallic minerals. In our 2023 campaign, we deployed multi-spectral hyperspectral imaging across 14 narrow infrared bands ranging from 940 to 1650 nanometers. This wavelength range penetrates the calcium sulphate surface without inducing thermal degradation. The resulting spectral reflectance maps exposed 27 previously unseen anthropomorphic figures carrying ceremonial staffs, rendered in an organic iron-gall and carbon-black mixture. Crucially, the stratigraphic software algorithm isolated the hidden pictorial profiles without altering the upper sixteenth-century drawings. This technical breakthrough confirmed that the original codex had been intentionally whitewashed around the year 1556 to repurpose the precious leather substrate for colonial records, rather than due to physical pigment deterioration."
According to the presentation, what specific technological method enabled the researchers to reveal the concealed figures beneath the manuscript's gesso primer?
- AApplying traditional radiography to detect the mineral opacity of metallic pigments embedded in the deer hide
- Capturing narrow-band infrared spectral reflectance maps that penetrate the calcium sulphate coating without thermal damageAnswer
- CMechanically scraping the calcium sulphate surface layer to recover figures degraded by physical wear
- DAnalyzing sixteenth-century colonial administrative texts to reconstruct the whitewashing timeline